1. Field of the Invention
The invention relates to a system for video editing and, particularly, editing of video sequences encoded to an object representation using object-based video encoding to implement a video coloring book.
2. Background of the Invention
In object-based video encoding (or representation), a video sequence is encoded as (or decomposed to or converted to) a decomposed video sequence comprising two streams, a first stream for a background composite of the video sequence and a second stream for foreground regions of the video sequence. The background composite is encoded only once in the first stream. On the other hand, the foreground regions are moving and are encoded for every frame of the video sequence in the second stream. The two streams of the object-based encoded video are then stored or transmitted. The video sequence is reconstituted by composing the decomposed video sequence to obtain a composite video sequence.
Object-based video encoding is different from traditional frame-based encoding, which uses only one stream. Through storing or transmitting the decomposed video sequence, significant savings in memory or bandwidth are achieved over traditional framed-based encoding in which each frame of the video sequence is stored or transmitted as a single stream. Additional memory or bandwidth savings can be achieved by compressing the two streams of the decomposed video sequence prior to storage or transmission. In addition to conventional approaches for object-based video encoding, generation of the background composite and the foreground regions is discussed in commonly-assigned U.S. patent application Ser. No. 09/472,162, filed Dec. 27, 1999, and Ser. No. 09/609,919, filed Jul. 3, 2000, both of which are incorporated herein by reference.
In conventional video editing, a video sequence is obtained, and the video sequence is edited on a frame-by-frame basis. To edit an aspect of the video sequence that appears over a number of sequential frames, each frame must be edited individually. Thereafter, if desired, the resulting modified video sequence may be encoded using object-based video encoding or any other type of video compression. This conventional technique is very laborious and time consuming.
In another conventional technique for video editing, the video sequence is encoded as a number of video layers. For each video layer, the content in the video layer changes for each frame. Further, no equivalent to the background composite discussed above for the object-based video encoding is obtained. To edit one of the video layers, a nonlinear editor (NLE) is typically used to edit the video layer on a frame-by-frame basis. To edit an aspect of the video sequence that appears over a number of sequential frames, each frame of the affected video layers must be edited individually. Although some NLE's have the ability to extrapolate a change to a frame in a video layer to a small number of frames in the same video layer forwards or backwards in time from the changed frame, this conventional video editing technique is likewise very laborious and time consuming.